[52.05] Massive Galactic Winds During Galaxy Formation

J.J. Binney (Oxford University)

Semi-analytic galaxy-formation theory assumes that baryons
conserve their angular momentum as they fall in to the
centers of dark halos. Even so the theory predicts that
galactic disks should be smaller than they actually are.
Since early dark halos are expected to be lumpy and
triaxial, baryons will in reality lose angular momentum as
they fall in - numerical simulations strongly confirm this
expectation. What becomes of low angular-momentum baryons?
Some, but not all may form a spheroid. It is likely that the
rest were ejected as a wind driven by a combination of the
AGN and bulge. Thus galaxy formation, like star formation,
may manifest itself more through bipolar outflow than
detectable inflow. The ejected baryons could have
significant impact on both later-infalling baryons and on
the center of the dark-matter halo.